In the electronics industry, there is a constant demand for electronic devices, such as integrated circuits or semiconductor chips, to be produced less expensively and in smaller dimensions. One way to increase productivity of such electronic devices, and thereby reduce their unit cost, is to increase the test speed of the devices by testing a plurality of them at the same time.
It has become a test technology standard to place a number of electronic devices to be tested on a test tray and position them so as to be engaged by a test head plate having a number of corresponding test contactors. One device is placed on a seat of a carrier module, and each carrier module is provided with one or more device seats. A number of modules are then positioned by column and row on a test tray. The test tray, having a number of such carrier modules, is arranged so as to be in vertical alignment (either above or below) with a test fixture.
The test fixture includes test contactors (test pins) for contact with the pins of each device to be tested for supplying and receiving the test signals from the device. Each module is aligned with a corresponding test contactor so that when either the test tray or the test fixture are moved in a vertical direction toward the other, the contactor engages the electronic device positioned within the carrier module.
The contactor is provided with a number of test pins or leads which come into electrical communication with the leads of the electronic devices to be tested. The automatic test handler is electrically connected to a electronic device test system, for example, an IC tester which includes a test signal generator for supplying a test signal to the device, and with a signal comparator for analyzing the results of the test. Based on such results, the electronic devices are transferred to another location in the test process and sorted for proper handling.
In test handling equipment of the prior art, a number of disadvantages have become apparent. First, even with such automatic handling equipment, there is a need for extensive handling of individual ICs or chips. For example, there is a need to remove the electronic devices to be tested from a container and to place the devices in an appropriate position on the test tray prior to testing. It is also necessary, following the test, to remove the tested devices from the test tray, to sort them based on the test results, and to replace the devices into their original containers for return shipping to the customer or other appropriate destination.
Because of recent demands in the electronics industry, various new types of IC packaging have been developed. Furthermore, containers for such new IC packages have also been developed and are changing in configuration from time to time. An example of such a container is ref erred to as a "customer tray," wherein a number of IC devices are aligned in a horizontal plane in a manner similar to the test tray, as described above. However, customer trays have not been standardized, and the size, shape, capacity and spacing between the seats of the devices vary widely from manufacturer to manufacturer. The spacing in the customer tray may also be different from that required for the test tray. This is particularly true since the test tray requires more accuracy for securing the perfect contact between the test contactor and the IC device leads. Although the customer trays themselves have not been standardized, the industry has standardized the containers, referred to as "cassettes" or "magazines," in which the customer trays are housed for storage and shipping.
The customer trays interact with previous handlers in two basic ways. First, customer trays full of untested ICs must be removed from their respective magazines and placed in a position so that the ICs are accessible for transfer to a test tray and subsequent testing. This phase of the IC handling is typically referred to as "loading." Secondly, empty customer trays must be placed in position with respect to the handler to receive tested and sorted ICs according to various test categories. Further, each customer tray must be returned to an appropriate magazine, again according to the tests categories. This phase of the operation is typically referred to as "unloading."
The mechanical devices of a test handler which accomplish loading and unloading are very important to the efficient operation of the handler. If delays are experienced in either facet, the throughput and thus the productivity of the handler will be decreased. In particular, the unload phase is likely to result in delays because of a need to sort the tested ICs. In the load phase, all of the ICs are treated alike, and the mechanical movements for transferring them to a test tray can be minimized, thus minimizing the time incurred. On the other hand, the sorting of tested ICs is more complicated and requires additional mechanical movement, thus incurring increased handling time.
Accordingly, there is a serious need in the integrated circuit industry for an automatic test handler which can overcome the problems and disadvantages described above in connection with loading and unloading of customer trays.